Here is the second letter from Pickacr:
Subject: Do you guys know what you're talking about?

  When I first read your article on the SRPP, several errors in the analysis of the circuit were apparent, but I decided to check my references to be sure. Now that I have gone through some articles and rechecked an Electrical Engineering reference, I am convinced you have no clue how an "SRPP" amplification stage works. This is not a "push-pull" amplifier, it is not even close. If the amplifier stage worked as you suggested, this would probably be the most non-linear amp you could imagine. It is an active load (i.e. constant current) gain stage, and is the building block for almost all current op-amps and digital computer circuits. In an IC the transistors are doped and trimmed to obtain the beta needed to operate the circuit in its most linear region. It is such an oversight to not see this circuit as an active load that I am almost embarrassed for the article you wrote.
   So why use an active load? The answer is simple. If you look at the curves for a typical triode (say the 12AX7), you can see the most linear transition from curve to curve would be a horizontal line drawn through the most linear parts of the curves. But a resistor will not intersect these lines horizontally, it has a slope determined by R = V/I. In an attempt to keep this slope as close to horizontal as possible and still keep the tube in its operating region, a high resistance is chosen (and therefore the load is an
attempt to approximate a horizontal intersection of the curves), but not so high as to make the tube inoperable. Is there a way to create this horizontal line that makes the triodes respond in the most linear region possible? Yes, use an active load. The new load line is simply a horizontal line drawn across the curves at the current the source is biased to. Why do this? Because if properly done, there is no way to achieve a more linear response from a triode; the input impedance becomes very high, the

output impedance very low, and the response of the stage very fast (hence their use in digital circuits). There are many more reasons to use an active load over a passive load, but I'll leave that for you to cover. Also, you talked about the gain stage as though it consisted of two different stages, it doesn't. When using an active load the two triodes must be viewed as a single gain stage, just like a load resistor and triode in a grounded grid amp. For more information on these type of gain stages, read the article in Audio Amateur issue 3/91, pgs. 43-46. The developer of the circuit topology used for the last decade wrote the article and explains its operation in greater detail.
   One last request, before publishing an article like this on the web, please be sure to do your homework. There is enough misleading information in this field without needing others to add to it
Pickarc

   Please, Pickarc, tell us which EE reference you consulted. We know that it was not Valley and Wallman's Vacuum Tube Amplifiers, as they clearly state in section 11-11,

"The circuit between Epp and Ep, comprising the plate load for the lower tube, resembles the constant-current source of fig.11-18, but without the battery it is not a actually a constant current device. It is merely the equivalent of a a simple resistance, of value rp + (mu + 1)Resistor, returned to Epp."

   This book is hard to find so here is a URL that does a very thorough examination of the SRPP:

http://web.tiscalinet.it/teodorom/SRPPauto.htm

   Unfortunately, it is in Italian, but it is easily decipherable as it comprises mostly math. The key portion is the three current paths, through the bottom triode, through the top triode, and through the load.